This invention relates to a process for the removal of particulate matter and sulfur oxides from waste gases such as flue gas. The invention also relates to an apparatus for carrying out such a process.
Because of increasingly stringent requirements on the abatement of air pollution, the removal of sulfur oxides from gas mixtures, in particular from hot waste gases containing relatively small amounts of sulfur oxides, such as flue gases and gases originating from roasting processes, has in the past few years become of great concern and technical importance.
In many cases these waste gases also contain particulate matter, in particular when they emerge from roasting processes or from electrical power plants (coal-fired and sometimes oil-fired ones), which must also be removed from the waste gases. It is possible to remove the particulate matter, which, generally, consists of small particles and is called "fly ash," from the waste gases before or after the removal of the sulfur oxides, e.g., by filtration, with cyclones or by electrostatical precipitation. Such measures, however, require large capital investment in addition to the capital cost of the separate facilities for sulfur oxide removal. Further, even with this very large capital investment there is no assurance of complete success since the state of the art on particulate matter removal is not sufficiently advanced to assure trouble-free operation in all instances.
Accordingly, it would be very desirable if a process could be developed for the removal of both particulate matter and sulfur oxides from waste gases, in which there is no need for costly separate installations for the removal of particulate matter.